A φ-otdr sensitivity enhancement method and device based on frequency drift dynamic compensation
A dynamic compensation, -OTDR technology, applied in the field of optical fiber, can solve the problem of frequency drift of the light source, and achieve the effect of improving the ability to capture low-frequency disturbance and reducing the demand for light source stability.
Active Publication Date: 2017-03-15
NANJING UNIV
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[0005] Common commercial light sources always have obvious frequency drift, even narrow linewidth light sources with high coherence
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[0038] Below in conjunction with accompanying drawing, technical scheme of the present invention is described in further detail:
[0039] Such as figure 1 Shown is a schematic flow chart of the method of the present invention, a Φ-OTDR sensitivity enhancement method based on frequency drift dynamic compensation, comprising the following steps:
[0040] Step 1. Use the light source to output continuous light, and divide the continuous light into two paths: probe light and local oscillator light;
[0041] Step 2. Modulate the probe light, and input the pulsed light into the sensing fiber to obtain the Rayleigh backscattered light signal;
[0042] Step 3: After coupling the local oscillator light with the Rayleigh backscattered light signal, an electrical signal is obtained through photoelectric conversion, and the electrical signal is processed to obtain the initial optical frequency f of the light source 0 The Φ-OTDR curve below, take it as a reference curve W ref (i-1), the...
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The invention discloses a phi-OTDR sensitization method based on dynamic frequency drift compensation. The phi-OTDR sensitization method comprises the following steps: actively scanning light source output frequency of a phi-OTDR according to an inner modulation or outer modulation method, thereby acquiring phi-OTDR curve groups of different light frequency points; performing cross-correlation calculation on phi-OTDR curves of different light frequency points, confirming the size and the direction of light source frequency drift, and feeding back output frequency of a control light source; in the data processing process, selecting phi-OTDR curves with the highest cross-correlation values from different curve groups as effective data, and abandoning other curves with relatively low cross-correlation values, thereby compensating curve distortion caused by light source frequency drift. The invention further discloses a phi-OTDR sensitization device. As cross-correlation calculation is performed on the phi-OTDR curves of different light frequency points so as to confirm the size and the direction of frequency drift, driving of a phase position modulator can be fed back, and the light source frequency drift can be compensated. By adopting the scheme of the invention, the requirements of a phi-OTDR sensation system on light source stability are reduced, and the capability of capturing low-frequency disturbance of the system is greatly improved.
Description
technical field [0001] The invention relates to the field of optical fiber technology, in particular to a Φ-OTDR sensitivity enhancement method and device based on frequency drift dynamic compensation. Background technique [0002] Strengthening border protection, improving energy security, and improving social security are the basic requirements for social stability and rapid economic development. The perimeter security monitoring of some important base facilities in various fields such as military defense, large-scale industrial and mining, and civil security is an effective means to avoid major economic losses and maintain social stability and development. With the continuous development of society, people's security awareness is constantly improving, and various security monitoring technologies are also constantly developing. The optical fiber intrusion sensor system based on optical time domain reflectometer OTDR has the advantages of distributed, high sensitivity, wid...
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IPC IPC(8): G01D5/36
Inventor 张益昕朱帆张旭苹王顺唐志强
Owner NANJING UNIV